Additive manufacturing system having variable cure arrangement

ABSTRACT

A head is disclosed for an additive manufacturing system. The head may include a nozzle configured to discharge a matrix reinforced with a fiber, and a plurality of light sources at least partially surrounding the nozzle. The plurality of light sources may be configured to enhance curing of the matrix. At least two of the plurality of light sources are configured to generate light within different spectrums.

RELATED APPLICATIONS

This application is based on and claims the benefit of priority from U.S. Provisional Application No. 62/417,709 that was filed on Nov. 4, 2016, the contents of which are expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to a manufacturing system and, more particularly, to an additive manufacturing system having a variable cure arrangement.

BACKGROUND

Extrusion manufacturing is a known process for producing continuous structures. During extrusion manufacturing, a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) is pushed through a die having a desired cross-sectional shape and size. The material, upon exiting the die, cures and hardens into a final form. In some applications, UV light and/or ultrasonic vibrations are used to speed the cure of the liquid matrix as it exits the die. The structures produced by the extrusion manufacturing process can have any continuous length, with a straight or curved profile, a consistent cross-sectional shape, and excellent surface finish. Although extrusion manufacturing can be an efficient way to continuously manufacture structures, the resulting structures may lack the strength required for some applications.

Pultrusion manufacturing is a known process for producing high-strength structures. During pultrusion manufacturing, individual fiber strands, braids of strands, and/or woven fabrics are coated with or otherwise impregnated with a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) and pulled through a stationary die where the liquid matrix cures and hardens into a final form. As with extrusion manufacturing, UV light and/or ultrasonic vibrations are used in some pultrusion applications to speed the cure of the liquid matrix as it exits the die. The structures produced by the pultrusion manufacturing process have many of the same attributes of extruded structures, as well as increased strength due to the integrated fibers.

Although pultrusion manufacturing can be an efficient way to continuously manufacture high-strength structures, the resulting structures may lack the form (shape, size, and/or precision) required for some applications. In addition, conventional pultrusion manufacturing may lack flexibility in the types of matrix that can be used and/or the cure-rates of those matrixes.

The disclosed system is directed to addressing one or more of the problems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a head for an additive manufacturing system. The head may include a nozzle configured to discharge a matrix reinforced with a fiber, and a plurality of light sources at least partially surrounding the nozzle. The plurality of light sources may be configured to enhance curing of the matrix. At least two of the plurality of light sources are configured to generate light within different spectrums.

In another aspect, the present disclosure is directed to another head for an additive manufacturing system. This head may include a nozzle configured to discharge a matrix reinforced with a fiber, a UV light source located adjacent the nozzle, and at least one additional light source located adjacent the nozzle. The at least one additional light source may be configured to generate at least one of infrared light and blue light. The UV light source and the at least one additional light source may be active at different times to create separate areas of illumination located at different sides of the head. The UV light source and the at least one additional light source may also be selectively active at the same time to create at least one overlapping area of illumination.

In yet another aspect, the present disclosure is directed to an additive manufacturing system. The additive manufacturing system may include a support, and a head mounted to the support. The head may have a nozzle configured to discharge a matrix reinforced with a fiber, and a plurality of light sources at least partially surrounding the nozzle. The plurality of light sources may be configured to enhance curing of the matrix. At least two of the plurality of light sources may be configured to generate light within different spectrums. The additive manufacturing system may also include a controller configured to regulate operation of the support and the plurality of light sources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of an exemplary disclosed manufacturing system;

FIG. 2 is a diagrammatic illustration of an exemplary disclosed head that may be used in conjunction with the manufacturing system of FIG. 1; and

FIG. 3 is a diagrammatic illustration of an exemplary disclosed process that may be performed by the system of FIG. 1 and the head of FIG. 2.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary system 10, which may be used to continuously manufacture a composite structure 12 having any desired cross-sectional shape (e.g., circular, polygonal, etc.). System 10 may include at least a support 14 and a head 16. Head 16 may be coupled to and moved by support 14. In the disclosed embodiment of FIG. 1, support 14 is a robotic arm capable of moving head 16 in multiple directions during fabrication of structure 12, such that a resulting longitudinal axis of structure 12 is three-dimensional. It is contemplated, however, that support 14 could alternatively be an overhead gantry also capable of moving head 16 in multiple directions during fabrication of structure 12. Although support 14 is shown as being capable of 6-axis movements, it is contemplated that any other type of support 14 capable of moving head 16 in the same or in a different manner could also be utilized, if desired. In some embodiments, a drive may mechanically couple head 16 to support 14, and may include components that cooperate to move and/or supply power or materials to head 16.

Head 16 may be configured to receive or otherwise contain a matrix material. The matrix material may include any type of matrix material (e.g., a liquid resin, such as a zero volatile organic compound resin; a powdered metal; etc.) that is curable. Exemplary resins include thermosets, single- or multi-part epoxy resins, polyester resins, cationic epoxies, acrylated epoxies, urethanes, esters, thermoplastics, photopolymers, polyepoxides, thiols, alkenes, thiol-enes, and more. In one embodiment, the matrix material inside head 16 may be pressurized, for example by an external device (e.g., an extruder or another type of pump—not shown) that is fluidly connected to head 16 via a corresponding conduit (not shown). In another embodiment, however, the pressure may be generated completely inside of head 16 by a similar type of device. In yet other embodiments, the matrix material may be gravity-fed through and/or mixed within head 16. In some instances, the matrix material inside head 16 may need to be kept cool and/or dark to inhibit premature curing; while in other instances, the matrix material may need to be kept warm for the same reason. In either situation, head 16 may be specially configured (e.g., insulated, chilled, and/or warmed) to provide for these needs.

The matrix material may be used to coat, encase, or otherwise surround any number of continuous reinforcements (e.g., separate fibers, tows, rovings, and/or sheets of material) and, together with the reinforcements, make up at least a portion (e.g., a wall) of composite structure 12. The reinforcements may be stored within (e.g., on separate internal spools—not shown) or otherwise passed through head 16 (e.g., fed from external spools). When multiple reinforcements are simultaneously used, the reinforcements may be of the same type and have the same diameter and cross-sectional shape (e.g., circular, square, flat, etc.), or of a different type with different diameters and/or cross-sectional shapes. The reinforcements may include, for example, carbon fibers, vegetable fibers, wood fibers, mineral fibers, glass fibers, metallic wires, optical tubes, etc. It should be noted that the term “reinforcement” is meant to encompass both structural and non-structural types of continuous materials that can be at least partially encased in the matrix material discharging from head 16.

The reinforcements may be exposed to (e.g., coated with) the matrix material while the reinforcements are inside head 16, while the reinforcements are being passed to head 16, and/or while the reinforcements are discharging from head 16, as desired. The matrix material, dry reinforcements, and/or reinforcements that are already exposed to the matrix material (e.g., wetted reinforcements) may be transported into head 16 in any manner apparent to one skilled in the art.

The matrix material and reinforcement may be discharged from head 16 via at least two different modes of operation. In a first mode of operation, the matrix material and reinforcement are extruded (e.g., pushed under pressure and/or mechanical force) from head 16, as head 16 is moved by support 14 to create the 3-dimensional shape of structure 12. In a second mode of operation, at least the reinforcement is pulled from head 16, such that a tensile stress is created in the reinforcement during discharge. In this mode of operation, the matrix material may cling to the reinforcement and thereby also be pulled from head 16 along with the reinforcement, and/or the matrix material may be discharged from head 16 under pressure along with the pulled reinforcement. In the second mode of operation, where the matrix material is being pulled from head 16, the resulting tension in the reinforcement may increase a strength of structure 12, while also allowing for a greater length of unsupported material to have a straighter trajectory (i.e., the tension may act against the force of gravity to provide free-standing support for structure 12).

The reinforcement may be pulled from head 16 as a result of head 16 moving away from an anchor point 18. In particular, at the start of structure-formation, a length of matrix-impregnated reinforcement may be pulled and/or pushed from head 16, deposited onto anchor point 18, and cured, such that the discharged material adheres to anchor point 18. Thereafter, head 16 may be moved away from anchor point 18, and the relative movement may cause the reinforcement to be pulled from head 16. It should be noted that the movement of reinforcement through head 16 could be assisted (e.g., via internal feed mechanisms), if desired. However, the discharge rate of reinforcement from head 16 may primarily be the result of relative movement between head 16 and anchor point 18, such that tension is created within the reinforcement. It is contemplated that anchor point 18 could be moved away from head 16 instead of or in addition to head 16 being moved away from anchor point 18.

One or more cure enhancers (e.g., one or more light sources, an ultrasonic emitter, a laser, a heater, a catalyst dispenser, a microwave generator, etc.) 20 may be mounted proximate (e.g., within, on, and/or trailing from) head 16 and configured to enhance a cure rate and/or quality of the matrix material as it is discharged from head 16. Cure enhancer 20 may be controlled to selectively expose internal and/or external surfaces of structure 12 to energy (e.g., light energy, electromagnetic radiation, vibrations, heat, a chemical catalyst or hardener, etc.) during the formation of structure 12. The energy may increase a rate of chemical reaction occurring within the matrix material, sinter the material, harden the material, or otherwise cause the material to cure as it discharges from head 16.

A controller 22 may be provided and communicatively coupled with support 14, head 16, and any number and type of cure enhancers 20. Controller 22 may embody a single processor or multiple processors that include a means for controlling an operation of system(s) 10 and/or 12. Controller 22 may include one or more general- or special-purpose processors or microprocessors. Controller 22 may further include or be associated with a memory for storing data such as, for example, design limits, performance characteristics, operational instructions, matrix characteristics, reinforcement characteristics, characteristics of structure 12, and corresponding parameters of each component of system 10. Various other known circuits may be associated with controller 22, including power supply circuitry, signal-conditioning circuitry, solenoid/motor driver circuitry, communication circuitry, and other appropriate circuitry. Moreover, controller 22 may be capable of communicating with other components of system 10 via wired and/or wireless transmission.

One or more maps may be stored in the memory of controller 22 and used during fabrication of structure 12. Each of these maps may include a collection of data in the form of lookup tables, graphs, and/or equations. In the disclosed embodiment, the maps are used by controller 22 to determine desired characteristics of cure enhancers 20, the associated matrix, and/or the associated reinforcements at different locations within structure 12. The characteristics may include, among others, a type, quantity, and/or configuration of reinforcement and/or matrix to be discharged at a particular location within structure 12, and/or an amount, intensity, shape, and/or location of desired curing. Controller 22 may then correlate operation of support 14 (e.g., the location and/or orientation of head 16) and/or the discharge of material from head 16 (a type of material, desired performance of the material, cross-linking requirements of the material, a discharge rate, etc.) with the operation of cure enhancers 20 such that structure 12 is produced in a desired manner.

In the embodiment depicted in FIG. 2, multiple different types of light-emitting cure enhancers 20 are connected to head 16 (e.g., surrounding a nozzle tip 24) and regulated by controller 22. For example, a cure first enhancer 20 a may be a UV-light source; a second cure enhancer 20 b may be an infrared-light source; a third cure enhancer 20 c may be a blue-light source, and a fourth cure enhancer 20 d may produce light in yet another spectrum. Each of these cure enhancers 20 may be selectively energized (e.g., by controller 22) to a particular level, to thereby effect a desired cure property of the particular matrix material discharging from head 16 at any given time.

In some embodiments, multiple different cure enhancers 20 may be used at the same time to create hybrid sources of cure energy. For example, when discharging a larger diameter, circular cross-section, multi-fiber, and/or generally opaque material (e.g., a carbon fiber based composite), all cure enhancers 20 may be activated by controller 22 at the same time and/or at a maximum output level. However, when discharging a smaller diameter, flat cross-section, single-fiber, and/or generally transparent material (e.g., a fiberglass based composite), only one or two types of cure enhancers 20 may be activated to a lesser degree by controller 22. In these embodiments, one or more of cure enhancers 20 may need to be focused and/or aimed, such that the energy produced by these sources overlaps on structure 12 (shown in FIG. 3) in a desired pattern. One or more adjustable lenses 26 and/or other devices may be used for this purpose.

The amount of energy produced by any combination of active cure enhancers 20 may be sufficient to cure the matrix in the composite material before structure 12 axially grows more than a predetermined length away from head 16. In one embodiment, structure 12 is completely cured before the axial growth length becomes equal to an external diameter of the matrix-coated reinforcement.

FIG. 3 illustrates exemplary patterns of light energy produceable by cure enhancers 20 that may be used to cure the matrix material within structure 12 as it discharges from head 16. FIG. 3 will be discussed in more detail in the following section to further illustrate the disclosed concepts.

INDUSTRIAL APPLICABILITY

The disclosed system may be used to continuously manufacture composite structures having any desired cross-sectional shape, length, density, and/or strength. The composite structures may include any number of different reinforcements of the same or different types, diameters, shapes, configurations, and consists, and/or any number and types of different matrixes. In addition, the disclosed system may allow for use with a variety of different nozzle tips 24 and for adjustable curing of a variety of discharging materials. Operation of system 10 will now be described in detail.

At a start of a manufacturing event, information regarding a desired structure 12 may be loaded into system 10 (e.g., into controller 22 that is responsible for regulating operation of support 14, head 16, and/or cure enhancer(s) 20). This information may include, among other things, a size (e.g., diameter, wall thickness, length, etc.), a contour (e.g., a trajectory), surface features (e.g., ridge size, location, thickness, length; flange size, location, thickness, length; etc.), connection geometry (e.g., locations and sizes of couplings, tees, splices, etc.), location-specific matrix stipulations, location-specific reinforcement stipulations, desired cure rates, cure locations, cure shapes, cure amounts, etc. It should be noted that this information may alternatively or additionally be loaded into system 10 at different times and/or continuously during the manufacturing event, if desired.

Based on the component information, a specific nozzle tip 24 and/or cure enhancer configuration may be connected to head 16, and one or more different (e.g., different sizes, shapes, and/or types of) reinforcements and/or matrix materials may be selectively installed within system 10 and/or continuously supplied into nozzle tip 24. For example, a nozzle tip 24 that is configured to discharge a flat ribbon of generally transparent fiberglass material or a nozzle tip 24 that is configured to discharge a round tow of generally opaque carbon fibers may be connected to head 16. In some embodiments, the reinforcements may also need to be connected to a pulling machine (not shown) and/or to a mounting fixture (e.g., to anchor point 18). Installation of the matrix material may include filling head 16 and/or coupling of an extruder (not shown) to head 16. Head 16 may then be moved by support 14 under the regulation of controller 22 to cause matrix-coated reinforcements to be placed against or on a corresponding anchor point 18.

Cure enhancers 20 may then be selectively activated (e.g., turned on/off, aimed, overlapped, and/or intensity-adjusted by controller 22) to cause hardening of the matrix material surrounding the reinforcements, thereby bonding the reinforcements to anchor point 18. With reference to the examples provided above, only cure enhancer 20 a operating a lower level may be necessary to sufficiently cure the flat ribbon of generally transparent fiberglass, while cure enhancers 20 b-d operating at higher levels may be necessary to sufficiently cure the round tow of generally opaque carbon fibers.

FIG. 3 illustrates exemplary patterns of energy that may be created around the tip end of nozzle tip 24 during discharge of composite material. These patterns may be created by selectively activating particular cure enhancers 20 alone or at the same time, such that corresponding illumination areas overlap to some extent. For example, a first illumination area 28 a may have a generally circular shape and be created by activation of first cure enhancer 20 a; a second illumination area 28 b may also have a generally circular shape and be created by activation of second cure enhancer 20 b; a third illumination area 28 c may also have a generally circular shape and be created by activation of third cure enhancer 20 c; and a fourth illumination area 28 c may also have a generally circular shape and be created by activation of fourth cure enhancer 20 d. In addition, any number of different hybrid illumination areas 28 f may be created by the simultaneous activation of two or more of cure enhancers 20 a-d. The hybrid illumination areas 28 f may have a range of different shapes, sizes, and intensities, depending on the number of cure enhancers 20 simultaneously activated and overlapping and/or based on aiming of adjustable lenses 26.

In some embodiments, it may be beneficial to coordinate angular alignment of head 16 with the locations of illumination areas 28 created by cure enhancers 20. In particular, as head 16 is moved by support 14 during material discharge, the discharging material may trail away from only once side of head 16 (e.g., from a side opposite a trajectory of head 16). If this side were not aligned with (e.g., if the discharging material did not pass through) a desired illumination area 28, curing of the discharging material may not occur properly. Accordingly, care should be taken to ensure that the discharging material trails through a specified illumination area 28.

Multiple methods may be used to ensure that the discharging material trails through the specified illumination area 28. In one example, head 16 may be rotated (e.g., by support 14) such that the discharging material is angularly aligned with a particular illumination area 28 (e.g., such that a particular cure enhancer 20 or set of cure enhancers 20 are located at the trailing side of head 16). In another example, lenses 26 may be used to aim the light energy produced by cure enhancers 20, such that the particular illumination area 28 is placed over the discharging material. In yet another example, cure enhancers 20 may themselves be moved (e.g., pivoted around a center axis by a corresponding actuator) around nozzle tip 24 at the end face of head 16. Other methods may also be implemented, if desired.

The component information may then be used to control operation of system 10. For example, the reinforcements may be pulled and/or pushed from head 16 (along with the matrix material), while controller 22 selectively causes support 14 to move head 16 in a desired manner, such that an axis of the resulting structure 12 follows a desired trajectory (e.g., a free-space, unsupported, 3-D trajectory). In addition, cure enhancers 20 may be selectively activated by controller 22 and/or adjusted to specific positions and/or orientations (e.g., via corresponding actuators) during material discharge from nozzle tip 24, such that a corresponding amount of energy from cure enhancer(s) 20 is absorbed by the discharging material at a desired location and in a desired shape. For example, controller 22 may selectively activate or adjust cure enhancer(s) 20 a-20 d based on at least one of a diameter, a shape, a number, and an opacity of the continuous reinforcement discharging from nozzle tip 24. Once structure 12 has grown to a desired length, structure 12 may be disconnected (e.g., severed) from head 16 in any desired manner. In some embodiments, adjustments may be made to cure enhancers 20 that are specific to anchoring processes, and different than adjustments made during general fabrication of structure 12. Controller 22 may implement these different adjustments automatically based on a phase of an ongoing fabrication process.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed systems and head. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed systems and heads. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A head for a continuous manufacturing system, comprising: a nozzle configured to discharge a matrix reinforced with a fiber; and a plurality of light sources at least partially surrounding the nozzle and configured to enhance curing of the matrix, wherein at least two of the plurality of light sources are configured to generate light within different spectrums.
 2. The head of claim 1, wherein at least one of the different spectrums includes UV light.
 3. The head of claim 2, wherein another of the different spectrums includes at least one of infrared light and blue light.
 4. The head of claim 1, wherein the plurality of light sources are active at different times to create separate areas of illumination located at different sides of the head.
 5. The head of claim 4, wherein the plurality of light sources are selectively active at the same time to create at least one overlapping area of illumination.
 6. The head of claim 5, wherein activation of the plurality of light sources is coordinated with discharge of the matrix and fiber.
 7. The head of claim 6, wherein the plurality of light sources are active only at a side of the head from which the matrix and fiber are trailing.
 8. The head of claim 1, further including at least one lens configured to aim light energy from the plurality of light sources.
 9. The head of claim 1, wherein the fiber is continuous.
 10. A head for an additive manufacturing system, comprising: a nozzle configured to discharge a matrix reinforced with a fiber; a UV light source located adjacent the nozzle; and at least one additional light source located adjacent the nozzle, the at least one additional light source being configured to generate at least one of infrared light and blue light, wherein: the UV light source and the at least one additional light source are active at different times to create separate areas of illumination located at different sides of the head; and the UV light source and the at least one additional light source are also selectively active at the same time to create at least one overlapping area of illumination.
 11. The head of claim 10, wherein the UV light source and the at least one additional light source are active only at a side of the head from which the matrix and fiber are trailing.
 12. An additive manufacturing system, comprising: a support; a head mounted to the support and including: a nozzle configured to discharge a matrix reinforced with a fiber; and a plurality of light sources at least partially surrounding the nozzle and configured to enhance curing of the matrix, wherein at least two of the plurality of light sources are configured to generate light within different spectrums; and a controller configured to regulate operation of the support and the plurality of light sources.
 13. The additive manufacturing system of claim 12, wherein at least one of the different spectrums includes UV light.
 14. The additive manufacturing system of claim 13, wherein another of the different spectrums includes at least one of infrared light and blue light.
 15. The additive manufacturing system of claim 12, wherein the controller is configured to selectively activate the plurality of light sources at different times to create separate areas of illumination located at different sides of the head.
 16. The additive manufacturing system of claim 15, wherein the controller is further configured to selectively activate the plurality of light sources at the same time to create at least one overlapping area of illumination.
 17. The additive manufacturing system of claim 16, wherein the controller is configured to coordinate activation of the plurality of light sources with discharge of the matrix and fiber.
 18. The additive manufacturing system of claim 17, wherein controller is configured to oriented a specified combination of the plurality of light sources at a side of the head from which the matrix and fiber are trailing.
 19. The additive manufacturing system of claim 12, further including at least one lens configured to aim light energy from the plurality of light sources.
 20. The additive manufacturing system of claim 12, wherein the fiber is continuous. 